ASCOMYCOTA | LECANOROMYCETES > CALICIALES > Physciaceae

Genus Phaeophyscia, meaning 'grey-brown and inflated' - from the general colour of the thallus and relationship with Physcia

Common name:            Mealy Shadow Lichen

Synonym:                    Physcia orbicularis

Habitat:                         Woodland, wayside trees (for this entry)

Substrata:                     Bark, but also stone and concrete

Growth form:                Corticolous (saxicolous)

Thallus:                  Foliose

Apothecia:                    Lecanorine, infrequent

BLS identity rating:        Graded 1/5 (identification should be straightforward)

Thallus usually rosette-shaped to around 3-4cm across, or irregular if confluent with others; composed of long, closely or more loosely appressed, palmate, radiating lobes, to 1.5mm wide, separate or overlapping; upper surface highly variable with several morphs having been described, colour ranging from pale grey brownish to greenish grey, or beige, brown or even brownish black when dry, turning greener when wet with pale specimens often becoming quite vivid; sometimes tinged orange towards the centre; covered with both laminal and marginal soralia, usually grey to blackish, but often whitish if abraded; underside blackish with numerous simple rhizines, which are darker towards the centre, but much paler where they protrude and are exposed around the margins.

Apothecia infrequent, urn-shaped at first, then sessile, up to 2mm dia., discs rough, reddish-brown, becoming darker with age, smooth thalline margin, sometimes wavy,   

Phaeophyscia orbicularis is a common and widespread species occurring primarily on nutrient-enriched bark of deciduous trees, mainly on the trunk and branches, but also on twigs; more likely to be found on exposed, woodland edge or wayside trees; but also on basic stone, and calcareous substrata, including concrete, in urban areas.   

Could be confused with Phaeophyscia endococcina or Phaeophyscia endophoenicea, but those species are rarely recorded and occur further north, so can be disregarded locally.